I have started some vegetable seeds indoors (SF/Bay Area) in small 1"x1" pods. The seeds have sprouted but not sure when is a good time to move them to 4" indoor pots before planting them in the outdoors vegetable box?
It's recommended that you wait until after the first true leaves appear before transplanting seedlings.
I plant my seeds into small grow-bags made of plant-fiber. The roots can then grow right through the bottom and when this happens i know it's time to transplant. I also seed mine outside so I don't need to harden off. And I can then plant without removing the grow bag minimizing root shock.